The present invention relates to a semiconductor device and, more particularly, to a technique which is effective when applied to the mounting of a plurality of semiconductor devices on the mounting face of a mounting board.
As a semiconductor device suitable for the reduced size or thickness of an electronic device, there is a semiconductor device having the TSOP (Thin Small Out-line Package) structure. In this semi-conductor device of the TSOP structure, for example, a semiconductor chip, constituted of a DRAM (Dynamic Random Access Memory), is encapsulated in a package made of resin.
This package is so formed as to have a rectangular plane shape. At and along one side face of the package, there are arranged a plurality of outer leads. These outer leads are individually so formed as to have a gull-wing shape and are individually connected electrically to a plurality of external terminals (bonding pads) arrayed on one side of a major surface of the semiconductor chip. On the other side face opposed to the one side face of the package, moreover, there are arrayed a plurality of outer leads. These outer leads are individually so formed as to have a gull-wing shape and are individually connected electrically with a plurality of external terminals which are arrayed on the other side of the principal face of the semiconductor chip. In short, the semiconductor device of TSOP structure is constructed of a two-way lead array structure in which a plurality of outer leads electrically connected to the semiconductor chip are individually arrayed on the two side faces of the package, opposed to each other.
Semiconductor devices of the TSOP structure thus constructed are regularly mounted over the mounting board of a memory card which is additionally connected to an electronic device such as a personal computer or office computer. This mounting is usually performed by printing the electrode pads (the land regions of the wiring), arranged over the mounting face of the mounting board, with pasty solder by a screen printing method, and by fixing the electrode pads of the mounting board and the outer leads of the semi-conductor devices with solder.
Incidentally, a semiconductor device of the TSOP structure is disclosed in Nikkei Maikurodevaisu [pp. 34 to 45, the June issue, 1990] issued by NIKKEI BP.